Herein, we develop a photocatalytic [4 + 1] annulation of vinyl aziridines with alkyl halides. The reaction appears to experience radical trigger kinetically favored β-scission of the vinyl aziridine C-N bond, generating transient nitrogen-centered radical, followed by sequential single electron oxidation, 5-exo-trig cyclization, and protonation. Significantly, an unprecedented annulation mode in which vinyl aziridines serve as four-atom synthons has been disclosed.

The narrow distribution with high thermostability of supported metal clusters are of critical importance for heterogeneous catalysis. In this study, we demonstrate that via precovering the ZnO surface with CO2 molecules, the deposited metals can be dispersed into high density of single atoms or ultrasmall clusters at room temperature. Scanning tunneling microscopy (STM) in combination with density-functional theory (DFT) calculations reveal that the surface binding strengths of Cu and Pd atoms are both enhanced, either through directed bonding to the pre-adsorbed CO2 or mediated by the enhanced electron transfer to the surface, which greatly raises their diffusion barriers. Importantly, even after CO2 completely desorb from the surface at elevated temperatures, the dispersion effect continues to play a role in retarding the sintering of metal particles, which is further enhanced via the gaseous CO2 molecules impinging on the surface from the atmosphere. This research highlights the significant capability of surface bound species and its atmosphere in tailoring the distribution and thermostability of supported metals, which may also bring fresh insights into the catalytic mechanisms under variously controlled atmospheric conditions.

Pre-extraction of lithium from spent lithium-ion batteries (LIBs) is highly required to obtain a high recovery rate of lithium. Here, we report an ethanol-water vapor thermal reduction approach in a sealed reactor to selectively recycle lithium and transition metal oxides (TMOs) from spent LIBs. Spent cathode materials were converted to LiOH and TMO by the reduction of water-alcohol vapor at a temperature of 350-400 degrees C. More than 99 % of the Li in LiCoO2 was selectively extracted from LiCoO2 at 370 degrees C for 2 h and at 400 degrees C for 0.8 h. The selective extraction is co-driven by water and alcohol that enable the reduction of LiCoO2 and release water-soluble LiOH and water-insoluble TMOs. In addition, the water-vapor thermal reduction method is applicable to selectively recovery Li from different types of cathode materials such as NCMs and lithium manganese oxide. The pre-selective extraction ensures a high lithium recovery rate and a reagent-saving manner. We envision that the vapor thermal recovery method could help recycle spent LIBs by an environmentally friendly and economically reasonable way.

We propose coupling electrochemical leaching with solvent extraction to separate and recover Li and Co from spent lithium-ion batteries (LIBs). Electrochemical leaching occurs in the aqueous electrolyte for converting solid LiCoO2 into soluble Li+ and Co2+, in which electrons act as reductants to reduce Co(III) to Co(II). Simultaneously, solvent extraction occurs at the interface of aqueous and organic phases to separate Co2+ and Li+. By capturing and utilizing the protons from P507, leaching yields for both Co and Li exceed similar to 7 times than acid leaching without solvent extraction. The extraction efficiency of Co2+ reaches 86% at 60 degrees C, 3.5 V, while simultaneously retaining the majority of Li+ in the H2SO4 solution. The total leaching amount was improved because the organic phase provides protons to help the leaching of Co2+, and the continuous extraction process of Co(II) maintains the low Co2+ concentration in the aqueous solution. The synergistic interaction between electrochemical leaching and solvent extraction processes significantly reduces the consumption of chemicals, enhances the utilization efficiency of protons, and simplifies the recovery process. The leaching kinetics of Li and Co both conforms well to the residue layer diffusion control model and the activation energy (E-a) values of the leaching for Li and Co are 4.03 and 7.80 kJ/mol, respectively. Lastly, the economic and environmental assessment of this process also demonstrates the advantages of this method in reducing inputs, lowering environmental pollution, and enhancing economic benefits.

Waste biomass is one of the promising feedstocks to supply syngas that can be used as fuels, chemicals, reductants, etc. However, the relationship between the component of biomass and the constituent of pyrolysis gas remains unclear. Here, we study the pyrolysis behaviors of various biomasses and reveal the relationship between the biomass components and gas compositions. Further, different pyrolysis gases are applied for the reduction of spent lithium cobalt oxide (LiCoO2) below 500 °C. The pyrolysis gas with a higher concentration of CO has a higher reductivity to convert LiCoO2 to CoO and Li2CO3 with a conversion rate close to 100% in 1 h at 500 °C. The biomass rich in cellulose and with a lower content of lignin tends to produce pyrolysis gas with a high concentration of CO, which comes from the deliberate breakdown of carboxyl, carbonyl, ether, and ester linkages. Moreover, LiCoO2 exerts catalytic functions over the deoxygenation and enhancement of oxygenates and single-ring aromatics. Overall, this paper offers a tailored approach to regulating biomass pyrolysis gases, enabling highly efficient battery recycling and syngas production.

The utilization of biomass-assisted pyrolysis in the recycling of spent lithium-ion batteries has emerged as a promising and reliable process. This article furnishes theoretical underpinnings and analytical insights into this method, showcasing sawdust pyrolysis reduction as an efficient means to recycle spent LiMn2O4 2 O 4 and LiNi0.6- 0.6- Co 0.2 Mn 0.2 O 2 batteries. Through advanced thermogravimetry-gas chromatography-mass spectrometry analysis complemented by traditional thermodynamic demonstration, the synergistic effects of biomass pyrolysis reduction are elucidated, with minor autodecomposition and major carbothermal and gasthermal reduction pathways identified. The controlled manipulation of transition metals has demonstrated the capability to modulate surface pyrolysis gas catalytic reactions and facilitate the preparation of composite materials with diverse morphologies. Optimization of process conditions has culminated in recovery efficiency exceeding 99.0 % for LiMn2O4 2 O 4 and 99.5 % for LiNi0.6Co0.2Mn0.2O2. 0.6 Co 0.2 Mn 0.2 O 2 . Economic and environmental analyses underscore the

A paired electrolysis approach for recovering valuable components from LiCoO 2 and LiFePO 4 has been developed. This process renders an efficient and clean leaching process with reduced energy input and secondary waste emissions.

Preventing metal deposition by cathodic reduction is a formidable challenge during transition-metal-catalysed electrosynthesis under direct current (d.c.) electrolysis conditions, especially for noble metal catalysis. To overcome the limitation of reductive metal deposition, we now report an asymmetric-waveform alternating current (a.c.) electrolysis protocol for silver-catalysed C–H phosphorylation, where our a.c.-based approach achieves smooth regeneration of the silver catalyst. A wide variety of alkynes, alkenes and (hetero)arenes are reactive under our a.c. electrolysis conditions, delivering the desired phosphite ester derivatives (88 examples) in good yields, whereas these products are often obtained in poor yields under d.c. electrolysis conditions. Notably, this protocol can be expanded to Pd- and Cu-catalysed C–H functionalization. This electrochemical metal-catalysis strategy is distinct from traditional d.c. electrosynthesis and has great potential to be used in the fine organic chemical industry.

The synthesis of diarylamine is extremely important in organic chemistry. Herein, a novel electrochemical reductive arylation of nitroarenes with arylboronic acids was developed. A variety of diarylamines were synthesized without the need for transition-metal catalysts. The reaction could be scaled up efficiently in a flow cell and several derivatization reactions were carried out smoothly. Cyclic voltammetry experiments and mechanism studies showed that acetonitrile, formic acid, and triethyl phosphite all played a role in promoting this reductive arylation transformation.

A general and effective protocol to synthesize alpha,alpha-dibromo aryl ketones has been developed via an electrochemical oxidative method. The reaction proceeds smoothly at room temperature in an undivided cell without the addition of external oxidants. In the reaction process, LiBr acts as both bromine source and supporting electrolyte. This electrooxidation strategy has good substrate applicability and functional group compatibility. Moreover, the reaction could be scaled up efficiently in a continuous flow cell. The target product could undergo further functionalization for the synthesis of some useful heterocyclic compounds.

[目的]深入认知树轮-气候要素之间的关系,揭示树木径向生长的主要限制性因素的相对贡献率及边际效应,以提升树轮在树轮生态学、树轮气候学研究中的应用价值.[方法]基于庐山地区日本柳杉树轮宽度资料和庐山气象站气象资料,采用树轮气候学方法研制树轮宽度年表,基于相关分析方法初步识别树木径向生长的主要限制性因素,进而利用增强回归树分析方法揭示了庐山日本柳杉径向生长的主要影响因素相对贡献及边际效应.[结果]正向影响庐山日本柳杉径向生长的因素按重要程度从大到小依次为当年1-3月平均最低气温(20.66％)、上年2-11月相对湿度(15.4％)、当年2-3月平均水汽压(9.47％),负向影响庐山日本柳杉径向生长的因素按重要程度从大到小依次为上年11月日照时数(20.81％)、上年5月最大日降水量(20.54％)、当年7月平均气温(13.11％);树轮-气候之间的关系在阈值范围之内具有较好的线性关系,阈值范围外则不具有线性关系.[结论]庐山日本柳杉径向生长受多种气候要素的综合影响,任一要素的影响均不是简单的线性关系,均存在明显的阈值效应.在分析树木径向生长对气候要素响应及进行树轮气候重建时,对边际效应问题应予以重视,以增强树轮-气候间关系的可信度及气候重建的可靠性.

医学博士研究生是国家培养的高层次医疗人才,其培养质量不仅关系到毕业生的职业发展,也与国家经济社会发展密切相关,优质的生源是人才培养质量的前提保障.武汉大学第一临床学院自2019正式实施医学博士研究生招录"申请考核制",本文以2018-2020年录取生源为例,科学客观分析各项生源特征数据的变化情况.结果显示,近年医学博士研究生录取总人数稳步增长,多数来自"双一流"建设高校或"985/211"高校,且自"申请考核制"实施后所招录生源科研成果呈显著上涨趋势.

在气候变化背景下,海绵城市改造热岛效应减缓效果成为人们最为关注的焦点问题之一,准确获取海绵城市改造前、后温度数据是精准评价海绵城市改造对城市热岛减缓效果的重要前提,气象观测站点往往距离海绵改造区具有较远的空间距离,其数据的不适用性极大限制了评价的开展.以武汉市青山、四新示范区为研究区,基于遥感监测、红外热成像技术,采用设立对比区法、以空间换时间法分别从宏观和微观上估算海绵区改造前后的温度变化,评估海绵城市建设对城市热岛效应减缓的效果.结果 表明:在宏观上,海绵城市改造对工业区(青山示范区)热岛效应减缓有一定效果,对原始开发程度较低地区(四新示范区)未体现出明显效果;在微观上,不同的改造方式、布设方式,甚至同一材料不同颜色等均对海绵改造热岛减缓效应有影响.设立对比区法、以空间换时间法能够为评价海绵城市改造对城市热岛减缓效果估算提供新的思路,具有很强的实用价值.

A method for electrochemical oxidative direct C(sp3)–H azolation under metal catalyst-free and external chemical oxidant-free conditions.

Compared with the reported intramolecular electro-oxidative cyclization of alkenyl amines or vinyl anilines for the preparation of pyrrolidines or indolines, the intermolecular version is less studied. Herein, this electrochemical intermolecular oxidative annulation of anilines and alkenes for the preparation of indolines proceeded under external oxidant-free conditions. The most noteworthy achievement of our work is the facile generation of indolines with quaternary centers at the 2-position. In addition, alkenes and anilines bearing various functional groups can be well tolerated. Remarkably, electrolyte-free conditions were used in an electrochemical flow cell, which shows the application potential of this method.

Cheap and widely available carboxylic acids are a class of ideal substrates to construct valuable compounds. As a candidate of decarboxylative reactions, the acid-based neutral N-hydroxyphthalimide ester undergoes a reductive decarboxylative process rather than a common oxidative decarboxylative process, which is a potential transformation mode for new reactions. In this work, we developed an electrochemical C(sp(3))-C(sp(2)) coupling of N-hydroxyphthalimide esters and N-heteroarenes without any catalysts. Remarkably, this electrochemical protocol can not only be directly realised by carboxylic acids in a one-pot fashion, but also be scaled up using a continuous-flow reactor.

Alcohol oxidation reactions are widely used for the preparation of aldehydes and ketones. The electrolysis of alcohols to carbonyl compounds have been underutilized owing to low efficiency. Herein, we report an electrochemical oxidation of various alcohols in a continuous-flow reactor without external oxidants, base or mediators. The robust electrochemical oxidation is performed for a variety of alcohols with good functional group tolerance, high efficiency and atom economy, whereas mechanistic studies support the benzylic radical intermediate formation and hydrogen evolution. The electrochemical oxidation proves viable on diols with excellent levels of selectivity for the benzylic position.

: In this study, a stable oxygen isotope chronology from tree-ring cellulose (δ 18 O) in Bashan fir( Abies forrestii ) from Mt. Shennongjia in Hubei Province was correlated with meteorology records of the Badong meteorological station, circulation index data, and sea surface temperature of the South China Sea (SST). The chronology spans the time period of 1790 - 2011. The results indicate that the tree-ring δ 18 O chronology is closely correlated with local climate factors. The tree-ring δ 18 O chronology has a significantly positive correlation with March to April monthly mean temperature, has a significantly negative correlation with June to July monthly mean precipitation and June to July monthly mean relative humidity. Meanwhile, the tree-ring δ 18 O chronology has a significantly positive correlation with February to March area index of the northern hemisphere subtropical high (5E-360), September area index of the South China Sea subtropical high (100E-120E), January polar vortex area index of the Pacific Ocean (Zone 2, 150E-120W), and April to May sea surface temperature of the South China Sea (SST). A significantly negative correlation was found between the tree- ring δ 18 O chronology and January southern oscillation index (SOI). These indicate that the tree- ring δ 18 O chronology records at a large scale of atmospheric circulation information.This study is helpful to further understand the potential value of tree ring stable oxygen isotopes in the past climate change studies in Mt.Shennongjia, and provide a scientific basis for further research on climate reconstruction.

Ethylene and ethyne are among the simplest two-carbon building blocks. However, quite limited methods can be applied to incorporate ethylene or ethyne into fine chemicals. Here we demonstrate a cobalt-catalyzed dehydrogenative C–H/N–H [4+2] annulation of aryl/vinyl amides with ethylene or ethyne by using an electrochemical reaction protocol. Significantly, this work shows an example of electrochemical recycling of cobalt catalyst in oxidative C–H functionalization reactions, avoiding the use of external chemical oxidants and co-oxidants. The electrochemical method provides a reliable and safe way for incorporating gas-phase ethylene or ethyne into fine chemicals. High reaction efficiency and good functional group tolerance are observed under divided electrolytic conditions.

利用汉江流域32个气象站1961～2016年逐日降水资料,分析了汉江流域降水时空分布特征,并探讨了海温及大气环流对流域降水的影响.结果表明:雨量和雨日空间分布相似,小雨、中雨的雨量和雨日由西南向东北递减,降水中心位于西南和东南部;流域东北部大雨以上量级降水由偏少转为偏多,而雨强空间分布则没有明显规律.流域降水集中度自东南向西北逐渐增加,降水集中期逐渐推迟.海温对降水的影响存在季节差异,春季、夏季和秋季降水分别受前期南印度洋、热带北大西洋和热带中东太平洋海温影响,冬季降水则受海温影响不明显;大尺度大气环流对降水存在影响,冬季欧亚遥相关型和春季西太平洋遥相关型均引起冬季风强度变化来影响冬季和春季降水,夏季副高位置和乌山阻高以及秋季巴湖低槽和印缅槽强度则均通过冷空气和暖湿气流强度及交汇位置来影响夏季和秋季降水.